Internal combustion engine with die cast block



Jan. 24, 1956 R, N. KIRCHER ET AL 2,731,960

INTERNAL COMBUSTION ENGINE WITH DIE CAST BLOCK Filed Oct. 29, 1952 4Sheets-Sheet 1 F le. 3

INVENTORS RALPH N. K IRCHER Y HERMAN D. PALMER A-r-ronuev Jan. 1956 R.N. KIRCHER ET AL 2,731,960

INTERNAL. COMBUSTION ENGINE WITH DIE CAST BLOCK 4 Sheets-Sheet 2 FiledOct. 29, 1952 Fla.

INVENTORS RALPH N. Kmcm-za HERMAN D. PALMER WMW ATTORNEY J 1956 R. N.KIRCHER ETAL 2,731,960

INTERNAL COMBUSTION ENGINE WITH DIE CAST BLOCK Filed Oct. 29, 1952 4Sheets-$heet 3 I26 I36 (28 Fla. 9

I38 Zoo I54 |58 am am INVENTORS RALPH N. KmcHeR BY HERMAN D. PALMER WMWATTORNEY Jan. 24, 1956 R. N. KIRCHER ET AL 2,731,960

INTERNAL COMBUSTION ENGINE WITH DIE CAST BLOCK Filed Oct. 29, 1952 4Sheets-Sheet 4 Fl ca. l3

INVENTORS F? RALPH N. K\RCHE.R BY HERMAN D. PALMER ATTORNE-Y INTERNALCQMBUS'HUN ENGINE WITH DIE CAST BLUCK Ralph N. Kircher, West Bend, andHerman D. Painter, Hartford, Wis., assignors to West Bend Aluminum (10.,West Bend, Wis., a corporation of Wisconsin Application Uctober 29,1952, denial No. 317,512

4 Claims. (Cl. 123-195) This invention relates to improvements ininternal combustion engines particularly to air-cooled engines havingdie cast blocks.

Many economies are effected by a die casting operation. But heretoforeonly a part of the possible savings have been obtained because only apart of the crankcase was cast with the cylinder block. Thisnecessitated additional complex machining operations in order to havethe crankshaft bearings properly alined and the resulting engine was notrigid and strong.

It is an object of this invention therefore to provide an engine of thistype which may be made by die casting to obtain the fullest economiesand is light, strong and rigid.

This object is obtained by die casting the engine block with thecylinder, cylinder head, cooling fins, fuel trans fer passage, cylinderwall insert if any, and all of the crankcase as one piece. The engineblock is cored so that both the cylinder-forming die and the transferpassage-forming die may be removed through a bottom or piston opening inthe crankcase. The dies for the bearing cage opens are withdrawnlaterally of the engine block along the axis of the crankcase; hencethere is established a fixed and rigid alinement for each crankshaftbearing. Any required machining is relatively simple and the casting maybe easily set up for drilling, boring, honing, or facing.

To assemble the engine the piston and piston rod assembly is firstintroduced into the cylinder through the piston opening in the bottom ofthe crankcase. The crankshaft is then inserted through the bearing cageopenings in the crankcase and the connecting rod bearing cap bolted inplace to secure the rod and crank. The hearing cages are then fitted onthe crankshaft and bolted rigidly in place in the bearing cage openings.Members comprising a reed valve plate and a carburetor connector arethen bolted to the crankcase over the piston opening. The crank andconnecting rod hearing, before the bearing cages are placed on thecrankshaft, may be positioned eccentrically of the bearing cage openingsso that the crank and bearing cap projects out through the pistonopening, making assembly of such cap very easy. However the pistonopening is large enough so that the connecting rod bearing cap can beeasily assembled even if the bearing cages have been put in place andthe crankshaft centered.

Several of such blocks can be used with a single crankshaft. In suchcase, center main bearing cages with crankshaft bearings are mounted onthe crankshaft be tween the cranks. Each cage fits into the bearing cageopenings of adjacent blocks and is gripped between such blocks which areheld by through-rods passing through arms on each block and each outerbearing cage.

In one modification of the invention the intake and exhaust ports are onthe same sides of the block as the bearing cage opening and the fueltransfer passage is formed by the same laterally removable die whichforms one of the bearing cage openings. In such modification the bearingcage has an extension which forms the outer wall of such transferpassage.

In another modification there is only one bearing cage opening and theopposite wall of the crankcase has an integral cylindrical projectionwhich forms the support for the other crankshaft bearing.

The novel features, which are considered characteristic of theinvention, are set forth with particularity in the appended claims. Theinvention itself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

Fig. l is a view in vertical cross-section of an internal combustionengine embodying the present invention;

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary view in right side elevation taken from the line3-3 of Fig. 1;

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 2;

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 2;

Fig. 6 is a fragmentary View in left side elevation taken from the line6-6 of Fig. 1;

Fig. 7 is a view in vertical cross-section of an internal combustionengine embodying a modification of the present invention;

Fig. 8 is a View in left side elevation taken from the line 8-8 of Fig.7;

Fig. 9 is a fragmentary sectional view of an internal combustion engineembodying a second modification of the present invention;

Fig. 10 is a fragmcntary view in right side elevation taken from theline 10-10 of Fig. 9;

Fig. 11 is a view partly in front elevation and partly in verticalsection of an internal combustion engine embodying a third modificationof the present invention;

Fig. 12 is a fragmentary sectional view taken on the line 12-12 of Fig.11, and

Fig. 13 is a fragmentary View in right side elevation taken from theline 13-13 of Fig. 11.

For the purposes of illustrating the present invention a conventionalform of two-cycle internal combustion engine employing a carburettedmixture has been employed. The cylinder structure of this type of enginereadily lends itself to the particular relationships by which it may bemade by economical die casting operation with the consequent eliminationof many machining operations without detracting from desired qualitiesof rigidity and long life operation.

Referring to Figs. 1 to 6 inclusive an air-cooled single cylinderinternal combustion engine is shown comprising a cylinder block 10 whichhas integral cooling fins 12 projecting from the cylinder wall. Aninsert or liner 14 of hardened metal constituting the bore of thecylinder may be cast in the cylinder or pressed therein after thecasting has been made. The cylinder block 10 has an integral head 16provided with a threaded opening in which is secured a conventionalspark plug. A crankcase 18 is also cast as an integral part of thecylinder block. The crankcase has a piston opening 20 in the bottomthereof of sufficient size to permit the introduction of a piston andthe liner 14- in cases when such liner is press fitted into the cylinderafter the casting. The crankcase 18 is also provided with oppositelypositioned axially alined bearing cage openings 22 and 24. Theseopenings are large enough in size to permit the longitudinal insertionof a crankshaft into the crankcase and form positive rigid support forthe bearing cages and crankshaft bearings.

On one side of the cylinder block there is an exhaust chamber 26 to theface of which is secured an exhaust pipe 28 by bolts 30. Exhaust ports32 are drilled in the floor of such chamber and liner 14 after thecasting operation. In order to introduce fuel intothe combustion chamberfrom the crankcase 18 an internal fuel transfer passage 34 is providedwhich extends upwardly within a pad 35 on the other side of the Wall ofthe cylinder block from the crankcase to an inlet chamber 36. The diefor this chamber is removed laterally so that the chamber has a sideopening to permit the inlet ports 38 to be drilled in the floor of thechamber and the liner 14 after the casting operation. The chamber isenclosed by a cover 40 held by bolts 42 to the face of such chamber. Thedie for the transfer passage 34 and the die for the cylinder bore arewithdrawn outwardly through the cylinder opening 2i) thus forming theintegral head.

When the cylinder block is made by a die casting operation the die forthe bore may have the liner 14 fitted thereon so that it will be castinto the wall of the cylinder. In other types of casting operations theliner 14 is pressed into the bore of the cylinder through the pistonopening 20. The dies for the exhaust chamber 26 and inlet chamber 36 arewithdrawn laterally with the opening of the mold. The casting thusformed may be easily jigged for the honing of the cylinder, the drillingof the ports, the surface boring of the inner wall of the bearing cageopenings, and the machining of the faces therearound. The fact that thewhole crankcase 18 is integral with the cylinder block makes a rigidconstruction. Each crankshaft bearing cage is accurately alined andrigidly held in such alinement.

A conventional piston 44 operates in the bore of the cylinder and hassecured thereto in the usual manner a connecting rod 46 having a crankbearing with a removable cap 48. This assembly without the bearing cap48 is first assembled into the block and moved to its uppermostposition. A conventional crankshaft 50 having a crank is then putlongitudinally through the bearing cage openings 22 and 24 with thecrank in alinement with the crank bearing on the rod 46. By the use of ajig or pusher red the piston and piston rod assembly is moved downwardlyso that the crank bearing on the rod will seat on the crank with thecrank in lowermost position. In this position the bearing cap 48 may bereadily installed and secured by the customary bolts and nuts 52.

A right hand bearing cage 54 having a plain bearing 56 is slid over theright end of the crankshaft 50 and seated in the bearing cage opening22. A flange 58 rests on the face around such opening 22 and the cage isheld to the block by stud bolts and nuts 60 or other like fasteningdevices. A left hand bearing cage 62 having spaced plain bearings 64-and 66 is slid over the left end of the crankshaft 50 and seated in theopening 24. A flange 63 on such cage rests on the outer face of suchopening and the cage is secured to the block by bolts 70 or other likefastening devices. In this particular embodiment the bearing cage 62 hasan extending flange 72-. provided with openings by which such flange canbe secured to a base for the purpose of mounting the engine.

The piston opening 20, after the assembly of the piston, crankshaft andthe bearing cages, is closed by a mounting member 74 which acts as asupport for a reed valve '76 and a carburetor.

By reason of the seats on the integral crankcase provided by the bearingcage openings, the bearing cages are accurately alined and rigidly heldin place.

In the modification of the invention embodied in the engine illustratedin Figs. 7 and 8 the exhaust and inlet ports are on the same diametricalsides of the cylinder as the crankshaft bearing cage openings. With thisarrangement the fuel transfer passage may be formed externally of thecylinder block and enclosed by a cover which is part of the bearingcage. This simplifies the 4- internal die and the removal thereof. Inthis modification the cylinder block is made by a die cast operation andhas the usual cooling fins 112. A cylinder liner 114 may be cast in atthe time of casting or pressed in later. The cylinder block has anintegral head 116 provided with a threaded opening in which is secured aconventional spark plug. A crankcase 118 is also cast integral with thecylinder block. It has a piston opening 120 in the bottom, a right sidebearing cage opening 122, and a left side bearing opening 124. Extendingupward from the opening 124 the block has a pad provided with alaterally opening recess forming a fuel transfer passage 134 extendingfrom the upper edge of such cage opening to an inlet chamber 136. Thecylinder block also has an exhaust chamber 126 to the face of which anexhaust pipe 128 is secured. Exhaust ports 132 and inlet ports 138 aredrilled in the floor of such chambers and the liner 114 after thecasting operation. The die for the cylinder bore is withdrawn throughthe piston opening 120 and the dies for the passage 134, chamber 136,and chamber 126 are withdrawn laterally with the mold.

The engine of this modification also has a conventional piston 144 andassembled piston rod 146 with a crank bearing including a removable cap143 secured by bolts 152. A crankshaft 150 of standard design isinserted longitudinally into the crankcase 118 through the bearing cageopenings 122 and 124. A right side bearing cage 154 with a plain bearing156 is slid over the right end of the crankshaft and fitted in thebearing cage opening 122. It has a flange 158 seated on the face of suchopening and secured to the block by conventional fastening means. A lefthand bearing cage 162 having plain bearings 164 and 166 is slid over theleft hand end of the crankshaft 150. It has an annular flange 168 whichseats on the outer face of the opening 124 and is secured thereto bybolts 170. This cage also has an upward extension 172 which forms theouter wall for the external fuel transfer passage 134 and the cover forthe chamber 136. Bolts 173 are used to hold the extension 172 tightlyseated against the outer face of such transfer passage. After assemblyof the cages 154 and 162 and the bearing cap 148 the piston opening 120is closed by a mounting member 174 which acts as a support for the usualreed valves and a carburetor.

In the modifications of the invention hereinbefore described bothcrankshaft bearings have been mounted in bearing cages secured asseparate elements to the block. It is possible, however, to eliminateone of the bearing cages as a separate element and cast one of thecrankshaft bearings integrally with the cylinder block. An engineembodying this feature is illustrated in Figs. 9 and 10. At the time ofthe casting of the cylinder block 200 the right side shaft bearingsupport 254 is cast integrally with such block and the usual plainbearing sleeve 256 is pressed into the bore of such support. The leftbearing of this modification is held in a cage opening in the crankcasethe same as illustrated in either of the two preceding modifications.The crankshaft 250 is inserted longitudinally through the left handbearing cage opening after the piston and piston rod unit have beenassembled. The left hand bearing cage is then inserted over the left endof the shaft 256 and the crank and rod connected. Thereafter the pistonopening 220 is covered by a support 274 in the identical manner aspreviously described.

The modification of the invention embodied in the engine shown in Figs.11, 12 and 13 illustrates how the cylinder block constructed like theembodiment of Figs. 1 to 6 inclusive may be used in a multi-cylinderengine. Each cylinder block is of identical construction andconsequently may be either a right hand or left hand block, that is, theintake side of each cylinder may be placed on the same side, eitherfront (as viewed in Fig. 11) or rear, or one may have the intake side onthe front and the other on the rear. A center main bearing cage andbearing are positioned on the center main bearing of the crankshaft andthe cylinders are mounted from opposite ends of the crankshaft so as toseat on such center main bearing cage. The cylinders and the outerbearing cages are held in assembled position by through-rods ashereinafter described in detail.

Each cylinder block 318 has cooling fins 312, a cylinder bore withinsert 314, an integral head 316, and an integral crankcase 318. Thefins on the left side of the right cylinder and the fins on the rightside of the left cylinder are cut away at 319 so that the cylinders maybe brought close enough to properly engage the center main bearing cage.The crankcase 318 of each cylinder has a piston opening 320 located inthe bottom thereof through which the piston and piston rod assembly maybe inserted into the cylinder. Each crankcase has a right side bearingcage opening 322 and a left side bearing cage opening 324. Extendingradially outwardly from the cylinder block adjacent each of theseopenings are rod receiving arms 323. An interior fuel transfer passageextends from the crankcase 318 to an inlet chamber 336, such passagebeing contained in a pad 335 integral with the front wall of eachcylinder. Inlet ports 338 leading to the interior of the cylinder aredrilled in the floor of the chamber 336 after the casting operation. Theinlet cham ber 336 after such drilling is closed by a cover 34!] securedto the cylinder block by bolts 342.

Each cylinder has a conventional piston 344 to which is connected a rod346 terminating in a crank bearing having a removable cap 348 secured bybolts and nuts 352. A split center main bearing cage 378 is mounted onthe center main bearing of a two-crank crankshaft 350. This cage has aperipheral fiange 380 and a bearing sleeve 382. The right hand cylinderblock with piston and piston rod assembled is slid over the right end ofthe crankshaft 250 until the bearing cage 378 fits in opening 324. Theleft hand cylinder block with piston and piston rod assembled is slidover the left end of the crankshaft 250 until the bearing cage 378 fitsin opening 322. The flange 388 is then engaged by the faces of suchopenings. The center main bearing may be a combination anti-frictionbearing and plainthrust bearing like that described and claimed in theapplication of Ralph N. Kircher, et a1., Serial No. 149,118, entitledMain Bearing for Multi- Crank Engine now Patent No. 2,614,897. It is notessential to this invention, however, that such center main bearing be acombined plain and anti-friction bearing. A plain hearing would besatisfactory provided it forms a pressure seal between the twocrankcases.

Instead of employing a single center main bearing cage and bearing, somestructural member such as a gear housing may be provided with separatebearing cages and bearings which will receive the ends of separatecrankshafts and over which the bearing cage opening 324 of the righthand cylinder block and bearing cage opening 322 of the left handcylinder block will fit to mount each cylinder.

After the cylinders have been assembled over the outer ends of thecrankshaft 350 and positioned on the center main bearing 378 a righthand bearing cage 354 having a bearing sleeve 356 is slid over the righthand end of crankshaft 250 and fitted in the bearing cage opening 322 ofthe right hand cylinder with its flange 358 resting on the face of suchopening. Rod receiving arms 359 project radially from this bearing cageand are alined with the arms 323 on the cylinder block. A left handbearing cage 362 having a bearing 364 is slid over the left end of thecrankshaft 350 and fitted in the bearing cage opening 324 of the lefthand cylinder with its flange 368 resting against the face of suchopening. This bearing cage also has radially projecting rod receivingarms 369 alined with the arms 323 on such cylinder. With the cylindersand bearing cages assembled as described, through-rods 334 are passedthrough the projecting arms and secured by nuts 386 to draw the outerbearing cages toward each other clamping the center bearing cage and thecylinders in a rigid position.

By manipulating the crankshaft 350 the cranks may be alternativelybrought into position adjacent the piston openings 320 and the pistonlowered so that the crank bearings on the rod rest on the cranks and thebearing caps 348 assembled and secured by bolts and nuts 352. When thisassembly has been completed for each cylinder the piston openings 320are closed by mounting members 374 which also act as supports forconventional reed valves and a connection for a carburetor manifold.

Although several embodiments of the invention are shown and describedherein, it will be understood that this application is intended to coversuch other changes or modifications as come within the spirit of theinvention or scope of the following claims:

We claim:

1. In an engine, the combination in a single casting of a cylinder withexternal radially extending cooling fins and an internal bore, saidcylinder having oppositely related inlet and exhaust chambersunobstructedly opening laterally outwardly of said cylinder; a head withexternal longitudinally extending cooling fins; a crank case havingwalls and a bottom defining an interior unobstructedly openingdownwardly from said cylinder bore and crank case interior, said crankcase bottom having an opening large enough to permit the insertoon of apiston into said bore; said cylinder having fuel transfer passageextending from the interior of said crank case to said inlet chamber;said crank case wall having a bearing cage opening large enough topermit a crankshaft to be inserted longitudinally into said crank case.

2. In an engine, the combination as defined in claim 1 in which saidcylinder has said fuel transfer passage unobstructedly opening laterallyoutwardly of said cylinder to define with said inlet chamber, saidtransfer passage and said bearing cage opening a continuous opening.

3. In an engine, the combination as defined in claim 1 in which saidcylinder has said fuel transfer passage unobstructedly openinglongitudinally downwardly into said crank case interior and separated bya wall from said bore, said transfer passage being spaced inwardly ofthe wall of said crank case interior.

4. In an engine, the combination as defined in claim 1 in which saidcylinder has a crankshaft bearing opposite said bearing cage opening andcoaxially alined therewith.

References Cited in the file of this patent UNITED STATES PATENTS1,465,165 Hall-Bullock Aug. 14, 1923 2,169,236 Frazier Aug. 15, 19392,218,332 Fowler Oct. 15, 1940 2,227,247 Conover Dec. 31, 1940 2,432,725Connelly Dec. 16, 1947 2,445,715 Jennings July 20, 1948 2,547,327 KingApr. 3, 1951 2,586,467 Jacobsen Feb. 19, 1952 FOREIGN PATENTS 25,771Sweden Mar. 14, 1906 32,802 Netherlands May 15, 1934

